class PriorityQueueTest(unittest.TestCase):
def setUp(self):
self.queue = PriorityQueue()
@istest
def starts_at_zero_size(self):
self.assertEqual(0, len(self.queue))
@istest
def can_push_an_elements(self):
self.queue.push('a')
self.assertEqual(1, len(self.queue))
@istest
def can_push_multiple_elements(self):
self.queue.push('a')
self.queue.push('b')
self.queue.push('c')
self.assertEqual(3, len(self.queue))
@istest
def can_pop_an_element(self):
expected_element = 'a'
self.queue.push(expected_element)
self.assertEqual(expected_element, self.queue.pop())
self.assertEqual(0, len(self.queue))
@istest
def can_pop_multiple_element(self):
expected_output = set(['a', 'b', 'c'])
for item in expected_output:
self.queue.push(item)
actual_output = set()
while self.queue:
actual_output.add(self.queue.pop())
self.assertEqual(expected_output, actual_output)
self.assertEqual(0, len(self.queue))
@istest
def can_pop_items_in_priority_order(self):
self.queue.push('a', 10)
self.queue.push('b', 50)
self.queue.push('c', 1)
self.assertEqual('c', self.queue.pop())
self.assertEqual('a', self.queue.pop())
self.assertEqual('b', self.queue.pop())
@istest
def no_priority_defaults_to_lowest_priority(self):
self.queue.push('a')
self.queue.push('b', 99)
self.assertEqual('b', self.queue.pop())
self.assertEqual('a', self.queue.pop())
@istest
def remove_elements(self):
self.queue.push('a', 9)
self.queue.push('b', 99)
self.queue.remove('a')
self.assertEqual(1, len(self.queue))
self.assertEqual('b', self.queue.pop())
self.assertEqual(0, len(self.queue))
@istest
def empty_queue_throws_key_error(self):
with self.assertRaises(KeyError):
self.queue.pop()
with self.assertRaises(KeyError):
self.queue.push('a')
self.queue.pop()
self.queue.pop()
with self.assertRaises(KeyError):
self.queue.push('b')
self.queue.remove('b')
self.queue.pop()
@istest
def can_update_priority(self):
self.queue.push('a', 99)
self.queue.push('b', 10)
self.assertEqual(2, len(self.queue))
self.queue.update('a', 3)
self.assertEqual(2, len(self.queue))
self.assertEqual('a', self.queue.pop())
self.assertEqual('b', self.queue.pop())
self.assertEqual(0, len(self.queue))
